Rodrigo Duterte wreaking vengeance on Senator De Lima over Davao drug war probe?

A student puts on a Halloween mask depicting President Rodrigo Duterte, at the college of fine arts of the University of the Philippines in Quezon city, metro Manila, PhilippinesReuters

Philippines senator Leila de Lima has filed a lawsuit against Rodrigo Duterte, seeking protection from the 'vengeful' president and accusing him of persecuting her.

De Lima, the former justice secretary, accuses the president and his allies of using her personal life to harass and abuse her incessantly.

"The question here is: can an incumbent president launch a personal vendetta against a person, against a woman," De Lima asks.

The senator says Duterte's grudge against her is long-standing. It dates back to the time when she was the justice secretary when, as a member of the Commission on Human Rights, she probed the president's drug war in Davao City.

In turn, the Duterte camp accuses De Lima of involvement in illegal drugs and of helping the drug cartel to expand reach. On a personal level, Duterte even accuses the senator of extra marital affairs -- charges that de Lima denies.

De Lima asks the court to stop Duterte from using her private life "outside the realm of legitimate public concern" to launch attacks against him. She also asks the court to order Duterte to stop making statements that malign her as a woman and "degrade her dignity as a human being".

The senator, however, acknowledges that Duterte enjoys immunity from the suit but wants her case to be a test case.

"This is a test case, a novel case of transcendental importance... Habeas data is rarely invoked. We are testing the doctrine of presidential immunity," she says.

"These verbal attacks and threats leveled against me are not covered by presidential immunity from suit because they are not the official acts of a President ... They constitute unlawful, unofficial conduct that have nothing to do with his duties," the senator said.

However, the Duterte camp said the senator was playing the gender card. "Senator De Lima's filing of a petition before the Supreme Court is calculated to generate media noise to drown out the accusations against her," they say.

Since Duterte won the election and took office on 30 June, the Philippine law enforcement and vigilante groups have killed more than 3,800 people as part of a campaign against drugs, which apparently will save the country.

While around 1,500 alleged drug peddlers died in police operations, others were killed by armed vigilante publicly encouraged by Duterte.

Last week another Philippine mayor linked to President Rodrigo Duterte's war on drugs was killed inside jail, the latest high-profile killing in the violence related to the president's much hyped drug war.

The week before that the mayor of Saudi Ampatuan, Samsudin Dimaukom, was shot dead along with nine members of his convey in a pre-dawn swoop in Maguindanao. The slain mayor figured in a list Duterte approved and published in August, which contained the names of drug peddlers and mafia operatives his government intended to eliminate.

Last week, another fierce critic of Duterte, Senator Antonio Trillanes launched another blistering tirade against President Rodrigo Duterte saying Filipinos should rethink about a leader who fails to keep his own promises and has acted against his own promises.